You want to know what the status Down Payment Status in the query Open Down Payment Requests of the Invoice Documents view in the Customer invoicing work center means.
Reproducing the Issue
Go to the Customer Invoicing work center.
Select the Invoice Documents view.
In the Show field select the Open Down Payment Requests option.
You can see that the displayed down payment requests have the down payment status Not Planned, Planned or Partially Planned.
You also notice that not all down payment requests created in the system are displayed.
This Down Payment Status, Not Planned, means the payment is cleared but not assigned to any invoice. If it was assigned to an invoice, the status will be changed to Planned or Partially Planned. Once the complete amount of the down payment was assigned to an invoice request it will not appear in the Open Down Payment Requests anymore.
KBA , AP-CI , Customer Invoice Processing , How To